In electronics, circuit boards such as printed circuit boards (PCBs) or main logic boards are used to mechanically support and electrically connect electronic components using conductive pathways, such as traces or members, etched from copper sheets laminated onto a non-conductive substrate. Alternative names are printed wiring board or etched wiring board. Circuit boards can include multiple planes or layers with the traces being routed across one or more of the planes or layers in order to connect electronic components.
After the circuit board is completed, electronic components can be attached to form a functional printed circuit assembly, or printed circuit board assembly (PCBA). In through-hole construction, component leads may be inserted in holes and electrically and mechanically fixed to the board with a molten metal solder, while in surface-mount construction, the components are simply soldered to pads or landings on outer surfaces of the PCB. Examples of electronic components include integrated circuits, transistors, capacitors, and resistors.
After the circuit board is populated, the interconnection between the traces or members and electronic components is typically tested to confirm connection between various components on the circuit board. Testing for correct component installation, electromagnetic compliance, electrostatic discharge issues, and for other purposes may also occur. The conductive traces or members are connected to test pads formed on the top or bottom surface of the circuit board. Typically, testing occurs with an array of probe tips contacting the test pads or test points on the top or bottom surface of the circuit board. Automated testing may occur with the execution of computer based software programs in a manufacturing test process to ensure functionality of electronic components mounted on circuit boards.
Recently, consumer electronic products have become very small. The circuit boards having electronic components internal to the consumer products have also decreased in size. Thus, as consumer products and circuit boards have decreased in size, the test points are restricted to a small surface area on a circuit board having a limited size.
Past testing processes have occurred with test pads or test points located at various regions on the top or bottom surface of the circuit boards. A test machine may have to move the array of probe tips from one region to the next to complete testing for a particular circuit board. The test pads may consume a significant portion of the top or bottom surface needed for mounting electronic components. The area consumed by the test pads increases the potential size of the circuit board and the resulting consumer products.